Presence of Plasma Globulins in the Hyaline Tissue in Cases of Silicosis

Abstract

PREVIOUS chemical results¹ obtained by one of us show that the hyaline tissue in cases of silicosis contains appreciable amounts of non-collagenous proteins. In fact the determination of the amino-acid composition, and the ultra-violet absorption spectrum of the residue left after extraction of collagen by autoclaving, suggested the presence of proteins chemically related to β- or γ-plasma globulins. These proteins constitute up to one-half of the total protein content of the original tissue. In order to ascertain beyond all doubt the presence in silicosis hyaline tissue of plasma globulins, it was decided to investigate whether proteins having the immunological properties of plasma globulins could be identified in it. Hyaline tissue was therefore isolated carefully from the pulmonary nodules of three cases of typical silicosis immediately after autopsy. The tissue was washed and homogenized in saline with a blade blendor (15 min. at 30,000 rev./min., excessive heat being prevented by water cooling). The resulting suspension was then washed and homogenized six further times with saline to remove all traces of serum or lymph. The serum of a rabbit previously immunized with normal human serum was absorbed twice with a third of its own volume of homogenized and washed silicosis hyaline tissue and was then used as antiserum for immunoelectrophoresis (using the technique of Grabar and Williams²). The antigens used were a pooled normal human serum electrophoretically separated in an agar plate; as a control, the same antiserum was absorbed with an equal amount of normal human lung treated in the same way as the silicosis hyaline tissue.